Understanding the potential impacts of global climate change to human health requires quantification of the sensitivity of human systems to climatic exposures and the extent to which social and infrastructure factors mediate those exposures. These relationships remain largely unknown for the case of diarrheal diseases, which are responsible for 2.5 million childhood deaths per year and transmission of which is strongly affected by climatic conditions. In order to meet this challenge, we will utilize an unparalleled dataset that is uniquely rich in all three dimensions of concern-disease, climate, and social vulnerability, including: 1) A five-year active surveillance dataset on weekly incidence of gastrointestinal disease for approximately 4,000 people living in 21 villages in rural Ecuador;2) Daily weather data for the same region available since 1965;and 3) a rich dataset on social and infrastructure conditions in these villages. The region presents an ideal study system because the communities vary according to key infrastructure and social variables related to social vulnerability factors but the overall climate across the region is similar. This offers an opportunity to not only provide much-needed data on climatic influences on GI disease risk, but to also examine how vulnerability of human communities can be used to explain variability in climate-disease relationships, under both current and projected future conditions. Our project addresses the following Specific Aims: SA1: For the period from 2003-2007: Establish relationships between weather (temperature, relative humidity, rainfall, and extreme rainfall) variables and incidence of gastrointestinal disease;SA2: For the period from 2003-2007: Examine how social vulnerability variables affect the relationship between weather and gastrointestinal disease;SA3: For two future time periods (2010-2035 and 2050-2080): Predict the expected prevalence of gastrointestinal disease in the study region given a range of climate change and social vulnerability scenarios. For this interdisciplinary, collaborative effort we have assembled a team of U.S. and Ecuadorian scientists with expertise in environmental epidemiology, socioclimatic analysis, tropical medicine, and health impacts of climate change with over seven years of experience in the study region. This proposal also incorporates extensive capacity building and training through workshops and symposia in Ecuador on climate and health, training of postgraduate students in Ecuador, and collaboration with and training of Ecuadorian scientists and students in the United States. PUBLIC HEALTH RELEVANCE: The proposed research examines the impact of climate variables on the incidence of gastrointestinal disease in rural Ecuador, both under current and projected future conditions, and how these relationships are mediated by social factors and infrastructure availability. The outcomes of the research will be used to determine the relative importance of social versus environmental (climate-related) factors in preventing gastrointestinal disease, and will help guide public health intervention strategies. The analysis will be useful both in the study area and also as a model system for understanding these processes in other parts of the world.